JPH01257311A - Iron core of ignition coil - Google Patents

Abstract

PURPOSE:To abolish a bracket used to fix a shift of a split body and to realize a small-sized and lightweight iron core by providing the following: an excitation part where a primary coil and a secondary coil are wound on its outer periphery; a closed magnetic circuit formation part which is installed collectively to be ring-shaped; and a permanent magnet which repels a flux produced by the excitation part. CONSTITUTION:A closed magnetic circuit formation part 520 is installed to be ring-shaped and collectively; accordingly, even when a force is exerted to the outward direction from the inside of the closed magnetic circuit formation part 520, the closed magnetic circuit formation part 520 is hard to deform even without any reinforcement. An excitation part 510 where a primary coil 310 and a secondary coil 320 have been wound on its outer periphery and a permanent magnet 530 which repels a flux produced by the excitation part 510 are housed at the inside; an electric current is supplied to the primary coil 310; a strong repulsive force is generated between the permanent magnet 530 and the excitation part 510 and between the permanent magnet 530 and the closed magnetic circuit formation part 520 (at each air gap). In this case, even when the closed magnetic circuit formation part 520 is not reinforced at all, the air gap is not widened or is hardly widened. By this setup a bracket for reinforcement use can be abolished; a small-sized and lightweight iron core can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an iron core of an ignition coil that stores magnetic energy.

[Prior Art] An ignition coil consists of a primary coil, a secondary coil, and an iron core. By supplying current to the primary coil, the iron core is excited and magnetic energy is accumulated, and the current is supplied to the primary coil. When the secondary coil is cut off, the accumulated energy becomes an induced electromotive force that generates a high voltage in the secondary coil, causing a spark discharge to occur in the ignition plug connected to the secondary coil.

On the other hand, in recent years, a permanent magnet has been installed in the magnetic loop of the iron core to repel the magnetic flux of the primary coil, increasing the amount of magnetic energy stored, improving ignition performance, and making the ignition coil smaller.
Lightweight devices are disclosed in JP-A-59-167006, TL, S, P, 4546753.

[Problems to be Solved by the Invention] On the other hand, in the iron core of the ignition coil, as shown in FIGS. 11 and 12, the primary coil 1 and the secondary coil 2 are wound around the outer periphery of the excitation part 3. It is composed of a plurality of divided bodies 4.5. Further, in order to arrange the permanent magnet 6 within the magnetic flux loop of the iron core, an air gap 7 for disposing the permanent magnet 6 is formed between the divided bodies 4.5.

The primary coil 1 of the ignition coil includes a permanent magnet 6.
When energized, a magnetic flux in a direction different from the magnetic flux of the permanent magnet 6 is generated in the excitation part 3. Due to this lick, the joining portions of the permanent magnet 6 and the divided body 4.5 repel each other, and the air gap 7 tends to separate.

If the repulsion of the magnetic flux separates the dividing body 4.5, not only will the stored magnetic energy decrease and ignition performance deteriorate, but the case of the ignition coil that covers the iron core will crack. If the case of the ignition coil cracks, it is very dangerous because the high voltage generated by the secondary coil will leak through the crack in the case.

For this reason, conventional iron cores equipped with permanent magnets 6 are fixed using non-magnetic brackets, bolts, etc. so that the divided bodies 4.5 do not move. As a result, the ignition coil becomes large and heavy, and the number of parts increases, resulting in an increase in manufacturing costs.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide an iron core for an ignition coil that eliminates the need for a bracket for fixing the movement of the divided body and realizes a reduction in size and weight.

[Means for Solving the Problems] In order to achieve the above object, the present invention has a primary coil and a secondary coil wound around the outer periphery, and
an excitation unit that is excited when the next coil is energized;
a closed magnetic path forming part that is integrally provided in an annular shape, houses the excitation part therein, and engages the magnetic flux generated by the excitation part; and a closed magnetic path forming part that repels the magnetic flux generated by the excitation part. The technical means includes a permanent magnet disposed in an air gap between the excitation section and the closed magnetic path forming section.

[Function] In the present invention having the above configuration, the closed magnetic path forming portion is annular and integrally provided, so even if a force is applied outward from the inside of the annular closed magnetic path forming portion, the closed magnetic path forming portion is not formed. The parts are much more difficult to deform than those with seams, even without equivalent reinforcement.

For this reason, an excitation part around which a primary coil and a secondary coil are wound, and a permanent magnet that repels the magnetic flux generated by the excitation part are housed inside, and current is supplied to the primary coil, and the permanent magnet If a strong repulsive force is generated between the permanent magnet and the excitation part, and between the permanent magnet and the closed magnetic circuit forming part, the permanent magnet and the excitation part, and the permanent magnet and the closed magnetic circuit, even if the closed magnetic circuit forming part does not have the same reinforcement. There is no or very little expansion between each of the formations (between the air gaps).

[Effects of the Invention] According to the present invention, even if current is supplied to the primary coil, the air gap does not widen due to the strength of the closed magnetic circuit forming part itself, so the reinforcing bracket used in the past can be abolished. can do.

By eliminating the reinforcing bracket, the ignition coil can be made smaller and lighter, and by reducing the number of parts such as brackets and mounting bolts, the manufacturing cost of the ignition coil can be kept low.

[Example] Next, the iron core of the ignition coil of the present invention will be described based on an example shown in the drawings.

1 to 4 show a first embodiment of the present invention, and FIG. 4 shows an example of an electric circuit of an ignition system 100 for an automobile.

The automobile ignition device ioo includes an igniter 200 that generates a de-energized ignition signal when igniting a gasoline engine (not shown) for driving the vehicle, a primary coil 310 that is switched between energized and de-energized by the igniter 200, and this primary coil 310. An ignition coil 3 including a secondary coil 320 that generates a high voltage when the coil 310 switches from a energized state to a non-energized state.
00, and an ignition plug 400 that receives high voltage from the secondary coil 320 of the ignition coil 300 and generates a spark discharge in an engine combustion chamber (not shown).

In the figure, reference numeral 110 indicates an on-vehicle battery, reference numeral 120 indicates a key switch, and reference numeral 130 indicates a fuse that protects the circuit by blowing.

Next, an ignition coil 300 to which the present invention is applied will be explained using cross-sectional views of FIGS. 1 and 2.

The ignition coil 300 is excited and accumulates magnetic energy when the primary coil 310 is energized, and when the primary coil 310 is de-energized, the magnetic energy accumulated during energization is released and the secondary coil 300 is activated. 320 is provided with an iron core 500 for generating an induced electromotive force.

The iron core 500 is disposed on the inner periphery of the primary coil 310, and
An independent excitation section 10 is provided which is excited and generates magnetic flux when the next coil is energized. This excitation section 510
This is a product in which a thin plate-like magnetic material (for example, soft iron) with oriented grains is punched into a substantially T-shape using a press, and then a plurality of press-molded products are laminated and press caulked, and one end has a wide and flat head 511. has been done. And this excitation section 510
is built in via an air gap A inside a closed magnetic path forming part 520 that closes the generated magnetic flux and forms a closed magnetic path when the primary coil 310 is energized and generates magnetic flux. .

Similar to the excitation part 510, the closed magnetic path forming part 520 is made by punching out a thin plate-like magnetic material (for example, soft iron) with oriented particles into a substantially square shape using a press or the like, and then laminating a plurality of press-molded products and press-caulking them. , a mouth-shaped annular portion is integrally provided. Note that ring portions 521 are provided on both sides of the closed magnetic path forming portion 520 of this embodiment, which are used when the ignition coil 300 is mounted on both sides.

The near gap provided between the excitation section 510 and the closed magnetic circuit forming section 520 is connected as shown in FIG.

A plate-shaped permanent magnet 530 is arranged so as to repel the magnetic flux generated when the excitation section 510 is excited, that is, so that adjacent surfaces thereof have the same polarity. This plate-shaped permanent magnet 530 is arranged over the entire width of the head 511 of the excitation section 510. The permanent magnet 530 uses a rare earth magnet such as a neodymium magnet or a rare earth-cobalt magnet, and generates a large magnetic force even if it is thin.

The primary coil 310 wound around the outer periphery of the excitation part blo is
The secondary coil 320 is wound around the outer periphery of an inner bobbin 610 that can house the excitation section 510 therein.
By inserting the excitation section 51G into the inner bobbin 610, the primary coil 310 and the secondary coil are wound around the outer circumference of the excitation section 510. A coil 320 is wound.

An excitation section 510, a closed magnetic path forming section 520, and a permanent magnet 5, each having a primary coil 310 and a secondary coil 320 attached to its outer periphery.
The assembled body in which the ignition coil 30 is assembled is housed in a case 700, and a casting resin 710 is injected and hardened to form the ignition coil 300. In addition, the ignition coil case 70
0 is a first case 720 equipped with a connector part 721 connected to the key switch 120 and the igniter 200, and a high voltage cord (not shown) connected to the spark plug 40G.
A second case 730 equipped with a high voltage terminal 731 to which is connected
Before combining the first case 72G and the second case 730, the various parts are electrically connected.

Next, the above operation will be described.

When the key switch 120 is turned on, the primary coil 310
and one end of the secondary coil 320 is connected to the vehicle battery 110
connected to. Then, the igniter 200 generates an ignition signal so that the primary coil 310 switches from a energized state to a de-energized state at the ignition timing, depending on the engine operating state such as the crank angle, rotational speed, load state, and cooling water temperature. are doing.

When the primary coil 31G is energized, the excitation section 510 of the iron core 500 is excited, and the excitation section 510 generates magnetic flux. The magnetic flux generated by this excitation section 510 is repelled by the magnetic flux generated by the permanent magnet 530 disposed in the air gap A.
Even if the magnetic flux generated by the secondary coil 310 is small, the iron core 50
0 can store large magnetic energy when energized.

Then, at the ignition timing, the primary coil 310 is connected to the igniter 20.
When the current is switched to 0, the magnetic energy stored in the iron core 500 is released, and an induced electromotive force is generated in the secondary coil 320 wound around the outer periphery of the iron core 500. Since the secondary coil 320 is thinner than the primary coil 310 and is wound around the outer periphery of the excitation section 510 in large numbers, a high voltage is generated in the secondary coil 320 due to the induced electromotive force. The high voltage generated by the secondary coil 320 is then applied to the ignition plug 400 to generate spark discharge within the engine combustion chamber.

After that, the igniter 200 energizes the primary coil 310 again and repeats the above process.

On the other hand, the primary coil 310 is energized and the excitation section bl.

When generating magnetic flux, the magnetic flux generated by the excitation section 510 repels the magnetic flux generated by the permanent magnet 530, so as shown in FIG. Due to the repulsive force between the closed magnetic path forming portion 520 and the closed magnetic path forming portion 520, the magnetic flux and the closed magnetic path forming portion 520 tend to separate from each other.

However, since the closed magnetic path forming part 520 is annular and integrally provided, even if force is applied outward from the inside of the closed magnetic path forming part 520, the closed magnetic path forming part 5
20 is much more difficult to deform than one with a seam even without the same reinforcement. Therefore, the excitation part 510 is excited, and the part between the permanent magnet 530 and the excitation part 510 and the permanent magnet 530 Even if E (near gap A) between and closed magnetic path forming portion 520 tries to separate from each other due to repulsive force, closed magnetic path forming portion 520 does not deform, so the air gap also does not expand.

In other words, according to this embodiment, even if a current is supplied to the primary coil 310 and a force is applied to widen the near gap A due to repulsion of magnetic flux, the near gap A will widen due to the strength of the closed magnetic path forming part b20 itself. I don't want to worry. Therefore, it is possible to eliminate the reinforcing bracket that was conventionally used to prevent the air gap from expanding.

And by abolishing this reinforcing bracket,
The ignition coil 300 can be made smaller and lighter than conventional ones, and the manufacturing cost of the ignition coil 300 can be kept low by reducing the number of parts such as brackets and mounting bolts.

In addition, since the conventional iron core had one magnetic flux loop (it was ring-shaped with an I-shaped excitation part and a U-shaped excitation path forming part, and there was one magnetic path), it formed a closed magnetic path. There is a magnetic flux path with low magnetic resistance that passes through the inner circumference of the part, and a magnetic flux path with high magnetic resistance that passes through the outer circumference, and the rate of change of the magnetic path increases, and the conversion efficiency between magnetic energy and electromotive force deteriorates. It had some problems.

However, in this embodiment, when the primary coil 310 is energized and the excitation section 510 is excited, the magnetic flux generated by the excitation section 510 is divided into two magnetic paths by the annular closed magnetic path forming section 520 and flows. . This slick reduces the rate of change in the magnetic path compared to the conventional iron core with one magnetic flux loop.
The conversion efficiency between magnetic energy and electromotive force can be improved compared to the conventional method, and the ignition coil 300 can be downsized.

FIG. 5 shows a second embodiment of the present invention.

In the embodiment described above, the excitation part 510 is provided in a substantially Go-shape, and the width of the head part 511 is made large, so that the permanent magnet 530
However, the iron core 500 shown in this embodiment is an example in which the excitation part 510 is provided in an oval shape, and the width of the head 511 is made large.

A third embodiment of the present invention is shown in FIGS. 6 and 7.

In the above embodiment, the lamination direction of the excitation part 510 and the lamination direction of the closed magnetic circuit forming part 520 are provided in the same direction, that is, in parallel, but in this embodiment, the lamination direction of the excitation part 510 is It is perpendicular to the 82 scrap direction of the path forming portion 520.

FIG. 8 shows a fourth embodiment of the present invention.

In the embodiment described above, the closed magnetic path forming part 520 is formed by laminating the press-molded parts in the shape of an opening, but in this embodiment, the closed magnetic path forming part 520 is formed by laminating the press-molded parts in the shape of a U-shape. The two divided bodies 522 and 523 are integrated by driving, welding, etc. so that they are joined at both ends of the excitation part 510.

Note that the junction of the two divided bodies 22 and 523 is the excitation part 5.
10, even if a repulsive force is applied across the near gap A, the joint will not separate (and the closed magnetic path forming portion 520 will not be deformed).

FIG. 9 shows a fifth embodiment of the present invention.

In this embodiment, two semi-cylindrical cores 5 each having a hollow interior are used.
24 and 525 are joined to form a closed magnetic path forming section 520.

As a result, the rate of change of the magnetic path is further reduced compared to the above embodiment, so that the conversion efficiency between magnetic energy and electromotive force can be further improved, and the ignition coil 30G
It becomes possible to further downsize. Note that the two semi-cylindrical cores 524 and 525 are provided with holes (not shown) for connecting the primary coil 310 and the secondary coil 320 to the outside.

FIG. 10 shows a sixth embodiment of the present invention.

In this embodiment, the length in the lateral direction of the closed magnetic path forming portion 520 (10th
(left/right direction in the figure) W and vertical length (vertical direction in Figure 10) L
were set so that W<L.

By making the closed magnetic path forming portion 520 have such a dimension ratio, the closed magnetic path forming portion 520 can be formed from a thin plate-like magnetic material (for example, soft iron).
20, the excitation part 510 can be pressed out at the same time as the closed magnetic path forming part 520 by using the inner part of the closed magnetic path forming part 520, as shown in FIG.

In addition, FIG. 10 shows the closed magnetic path forming part 5 during press punching.
20 and the arrangement of the excitation section 510.

As shown in the first embodiment, when the closed magnetic path forming part 520 is punched out in the shape of an opening in order to suppress the repulsive force of the permanent magnet 530, the inner part of the closed magnetic path forming part 520 becomes scrap. , yield becomes worse. Therefore,
As in this embodiment, by pressing out the excitation part 510 using the inner part of the closed magnetic path forming part 520, the yield of the iron core 500 can be improved.

[Brief explanation of the drawing]

1 to 4 show a first embodiment of the present invention, in which FIG. 1 is a front sectional view of the ignition coil, FIG. 2 is a side sectional view of the ignition coil, and FIG. 3 is the same as that shown in FIG. 1. FIG. 4 is a partial sectional view, FIG. 4 is an electric circuit diagram of an automobile ignition system, FIG. 5 is a plan view of an iron core showing a second embodiment of the present invention, and FIG. 6 is a plan view of an iron core showing a third embodiment of the present invention. 7 is a sectional view taken along line I-I in FIG. 6, FIG. 8 is a plan view of an iron core showing a fourth embodiment of the present invention, and FIG. 9 is a plan view of an iron core showing a fifth embodiment of the present invention. FIG. 10 is a layout diagram of an iron core at the time of pressing out, showing a sixth embodiment of the present invention, and FIGS. 11 and 12 are a perspective view and a plan view showing a conventional iron core. .

Claims (1)

[Scope of Claims] 1) (a) An excitation part having a primary coil and a secondary coil wound around its outer periphery and which is excited when the primary coil is energized; (b) an excitation part having an annular shape; (c) a closed magnetic path forming part that is integrally provided, houses the excitation part therein, and closes the magnetic flux generated by the excitation part; An iron core of an ignition coil including a permanent magnet disposed in an air gap between the closed magnetic path forming part and the closed magnetic path forming part.